Pin pull-up

On some GPIOs, you can enable built-in pin pull-up for resistors to +3.3 V in the processor.

Here Device Tree:

			pinctrl@80018000 {
				pinctrl-names = "default";
				pinctrl-0 = <&hog_pins_a &pin_gpio_pu_0_2 &pin_gpio_pu_0_3 &pin_gpio_pu_0_4>;

				hog_pins_a: hog@0 {
					reg = <0>;
					fsl,pinmux-ids = <
						0x2013 /* MX23_PAD_SSP1_DETECT__GPIO_2_1 */
						0x0113 /* MX23_PAD_GPMI_ALE__GPIO_0_17 */
					>;
					fsl,drive-strength = <0>;
					fsl,voltage = <1>;
					fsl,pull-up = <0>;
				};

				led_pin_gpio2_1: led_gpio2_1@0 {
					reg = <0>;
					fsl,pinmux-ids = <
						0x2013 /* MX23_PAD_SSP1_DETECT__GPIO_2_1 */
					>;
					fsl,drive-strength = <0>;
					fsl,voltage = <1>;
					fsl,pull-up = <0>;
				};


				pin_gpio_pu_0_2: pin_gpio_pu_0_2@0 {
					reg = <0>;
					fsl,pinmux-ids = <
						0x0023 /* MX23_PAD_GPMI_D02__GPIO_0_2 */

					>;
					fsl,drive-strength = <0>;
					fsl,voltage = <1>;
					/* enable 47K pull-up for TB9 gpio */
					fsl,pull-up = <1>;
				};

				pin_gpio_pu_0_3: pin_gpio_pu_0_3@0 {
					reg = <0>;
					fsl,pinmux-ids = <
						0x0033 /* MX23_PAD_GPMI_D03__GPIO_0_3 */

					>;
					fsl,drive-strength = <0>;
					fsl,voltage = <1>;

					/* enable 47K pull-up for TB10 gpios */
					fsl,pull-up = <1>;
				};

To turn off replace "fsl,pull-up = <1>;" with "fsl,pull-up = <0>" 23 / 10000 in the relevant block

List of GPIOs with pin pull-up

0-7
92
91
66
18-22 (10k)